Abstract (30 lines) Adolescent substance use is a significant public health problem that predicts future substance use disorders in adulthood. Precise understanding of risk factors is needed to develop and target preventions. A large body of research has identified the parenting environment as a strong risk factor for adolescent substance use. However, the brain mechanisms for effects of parenting on substance use are not known. In our current NIDA-funded R01 study, we found that maladaptive parenting behaviors measured in our novel laboratory parent-adolescent interaction task (PAIT) significantly predicted current and future (1 year later) substance use in 245 early adolescents. As a next step, in this R01 renewal application, we propose to team with a neuroscientist (co-PI Thompson) to investigate emotion- and reward-related brain mechanisms of effects of parenting on adolescent substance use. We conducted a pilot fMRI study with 72 of the adolescents from the R01 study and found initial evidence that observed parenting behaviors in the laboratory PAIT task predicted altered fronto-limbic-striatal activation to negative emotion and reward and that these brain responses predicted future adolescent substance use. Further, we found that these brain pathways differed by gender, with girls showing a pathway characterized by heightened fronto-limbic activation to negative emotion and boys showing a pathway characterized by heightened fronto-striatal activation to reward. The proposed renewal study will formally examine gender-differentiated brain pathways from parenting to adolescent substance use in a large sample with a greater range of parenting behavior. We will recruit 326 substance-naive 11-12 year olds and their parents, with 40% oversampled for maladaptive parenting. In a laboratory session, we will measure observed parenting behaviors and adolescent physiological responses in our PAIT task, validated in the current R01 study. Adolescents will complete fMRI sessions to examine brain functional activation (and also functional connectivity) in standardized emotion processing, reward processing, and resting-state tasks which we piloted in the current R01 sample. We will collect detailed behavioral and biological measures of substance use and problem use, emotion and reward sensitivity, and reported parenting at baseline and 1, 2, and 3 year follow-ups into middle adolescence. We will examine: 1. Parenting in PAIT predicting adolescent emotion- and reward-related brain function by gender and 2. Adolescent brain function predicting increases in substance use over three years, by gender. The study will be the first to integrate laboratory assessment of parenting with neuro- imaging to understand brain-based mechanisms of parenting effects on substance use. By identifying brain mechanisms of parenting effects, and gender differences in these, we can better target and strengthen parenting-focused prevention programs and develop gender-sensitive preventions.